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https://issues.apache.org/jira/browse/AMQ-4196?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13509052#comment-13509052
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Arthur Naseef commented on AMQ-4196:
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Is this a fully robust solution? Given the impact of missing consumers on
removal of a temporary destination (memory leak, leaked destinations, and
leaked threads), the removal of all consumers when the temporary destination is
deleted seems important to keep all the way around.
In addition, the nature of advisories includes sending destination removals and
consumer removals through different destinations, and therefore different
threads (dest remove on ActiveMQ.Advisory.TempQueue/TempTopic and consumer
remove on ActiveMQ.Advisory.Consumer.ID...) which also leads to out-of-order
processing. In this case, the change here will have no impact.
> Race condition between removal of subscriptions and removal of destinations
> in a network of brokers
> ---------------------------------------------------------------------------------------------------
>
> Key: AMQ-4196
> URL: https://issues.apache.org/jira/browse/AMQ-4196
> Project: ActiveMQ
> Issue Type: Bug
> Components: Broker, Connector
> Affects Versions: 5.6.0, 5.7.0
> Reporter: Gary Tully
> Assignee: Gary Tully
> Labels: Temp, networkBridge
> Fix For: 5.8.0
>
>
> n a broker network like this: A <--> B <---> C
> Scenario:
> A producer to BrokerA creates a message, sets its replyTo header to a temp
> destination that it creates and listens on, then sends the message off to
> broker A. The message is demand forwarded to BrokerC because there is a
> consumer there that consumes the message and replies to the temp dest in the
> replyTo header.
> As the number of concurrent producers on BrokerA sending these messages
> increases, the subscription to the temp destination that was demand forwarded
> will not be cleaned up properly on BrokerC. The reason for this is the
> DemandForwardingBridge runs the remove consumer code in a separate thread.
> But if a "remove destination" advisory messages comes in, it will remove the
> destination from the AdvisoryBroker's destination map. So if this happens
> before the code for removeConsumer runs (in AdvisoryBroker), then the
> destination will not be in the destination map and the advisory for
> removeConsumer will not fire.
> The net result is a subscription leak in the network bridge on B & C
> The junit test shows two issues:
> 1) the subscriptions leaked when concurrent producers using request/reply and
> correctly closing the consumer and connection
> 2) all subscriptions leaked when using a single producer with request/reply
> and closing only the connection, and not the consumer explicitly
> Issue 2 is related to temp destinations only and is compounded by
> https://issues.apache.org/jira/browse/AMQ-3879
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